what is the ideal rental bike?

For brand recognition and quality, seems like it should be a major brand, such as trek or giant. I think for most people in the city a hybrid bike is the most useful (no need for a mountain bike and a road bike is hard to ride and more likely to get flats). Then the question is what are the big sellers? For trek the top seller is apparently the trek 7.1 FX. So far I've focused on the 7100, but the 7.1 is very similar.
http://www.trekbikes.com/us/en/bikes/road/fitness/fx/7_1_fx/